The urban development of farmland in California's Central Valley
(click image for larger version)

The 400 mile long stretch of central California that is the Central Valley
has one of the highest rates of development in the country, with farmland
being paved over to construct new residential suburbs and giant retail
outlets. In terms of city income, this has both beneficial and detrimental
effects.

Increased development attracts more people, thus increasing revenue for
the city (whether from property tax, sales tax or utility fees). However,
the previously agricultural land requires new infrastructure to be constructed
(sewers, roads) and an increase in annual maintenance fees (including
emergency services, schools, etc.). The increased income must also be
weighed against contributions to the local economy made by the old farmland
which required far less infrastructure. A further detrimental effect is
that new construction causes the value of nearby property to drop --most
people would prefer to move into the new suburbs rather than those which
are a few years old -- resulting in a corresponding drop in city revenue
from property taxes.

With new income not matching new expenses, cities have been forced to
take on bond debt to make up the shortfall, with the cost of this due
to be paid by increased taxes and fees on future residents and developers.
With expenditure continually increasing and income not keeping pace, the
reinforcing loop of bonds and repayment is set to stay unless the contributing
factors in the system are changed.

One solution would be to enforce land use restrictions making developers
rebuild on more central, previously developed, land. If "Development
on undeveloped land" in the diagram were replaced with "Redevelopment"
we could remove the downward force on "Amount of farmland" (leaving
its tax contribution intact), and the negative effect on neighbouring
property values would be reduced. Additionally, we could remove the need
for new infrastructure, thus halting the increase in expenditure.

An alternative would be to force developers to pay the infrastructure
costs themselves, again relieving pressure on city expenditure. This move
is unlikely to be popular with developers, smart growth enthusiasts or
the home buyers who would see themselves footing the bill with increased
house prices.

(Source: Ecology of Fear, Mike Davis, pp95-112.)

The relationship between hurricane frequency and atmospheric temperature
(click image for larger version)

There are two factors relating the frequency of hurricanes and the temperature
of the Earth's atmosphere, creating a systems of positive feedback which
causes both to rise. Computer modelling implies that as the planet warms
up the frequency and intensity of hurricanes will both increase. Global
temperature already seems to be rising due to the amount of carbon dioxide
human activity is releasing into the air, but it appears that hurricanes
themselves can add to the problem: such a storm can be so powerful that
carbon dioxide is pulled from the sea's surface and released into the
atmosphere. At the moment this contribution is only 1/12 the size of the
carbon dioxide emissions released by human activity, but this could rise,
depending on the strength of the positive feedback loop. Cutting our own
contributions would of course slow the process dramatically.